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Commit 90fa1527 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
Browse files

dm snapshot: change yield to msleep 



Change yield() to msleep(1). If the thread had realtime priority,
yield() doesn't really yield, so the yielding process would loop
indefinitely and cause machine lockup.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent a1b51e98

drivers/md/dm-snap.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/blkdev.h>

#include <linux/blkdev.h>

#include <linux/ctype.h>

#include <linux/ctype.h>

#include <linux/device-mapper.h>

#include <linux/device-mapper.h>

#include <linux/delay.h>

#include <linux/fs.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/init.h>

#include <linux/kdev_t.h>

#include <linux/kdev_t.h>
@@ -735,7 +736,7 @@ static void snapshot_dtr(struct dm_target *ti) 
	unregister_snapshot(s);

	unregister_snapshot(s);





	while (atomic_read(&s->pending_exceptions_count))

	while (atomic_read(&s->pending_exceptions_count))

		yield();

		msleep(1);

	/*

	/*

	 * Ensure instructions in mempool_destroy aren't reordered

	 * Ensure instructions in mempool_destroy aren't reordered

	 * before atomic_read.

	 * before atomic_read.
@@ -888,10 +889,10 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success) 




	/*

	/*

	 * Check for conflicting reads. This is extremely improbable,

	 * Check for conflicting reads. This is extremely improbable,

	 * so yield() is sufficient and there is no need for a wait queue.

	 * so msleep(1) is sufficient and there is no need for a wait queue.

	 */

	 */

	while (__chunk_is_tracked(s, pe->e.old_chunk))

	while (__chunk_is_tracked(s, pe->e.old_chunk))

		yield();

		msleep(1);





	/*

	/*

	 * Add a proper exception, and remove the

	 * Add a proper exception, and remove the